1. Field of the Invention
This invention relates to a process and apparatus for monitoring the cleaning of a surface by laser irradiation.
2. Discussion of Prior Art
In many manufacturing processes such as for aircraft and automobiles components have to be cleaned prior to joining or coating. Conventionally this task is performed by wet cleaning using either water jets or solvents. In both cases the liquid residue remaining after cleaning has to be disposed of. Due to the impact of the solvents or the residue containing liquids upon the environment and the costs associated with the disposal of these chemicals, alternative cleaning techniques are desirable which do not involve the use and disposal of environmentally hazardous chemicals or residues.
It has been proposed to use a cleaning process which involves the irradiation of a surface by laser to remove contaminants such as solvents or epoxy particles. However it is also advisable to monitor the effectiveness of such laser cleaning processes and techniques have been proposed for doing this by plasma or ion emission analysis. One of the disadvantages of such monitoring techniques is that they can only monitor the very area the laser pulse is cleaning and no analysis can be performed on the area that is to be cleaned or the area that has been cleaned. Additionally the analysis process is time consuming and relatively expensive to carry out.
There is thus a need for a generally improved and simplified process of monitoring the cleaning of a surface by laser irradiation which can be used more effectively across the whole area of the surface to be cleaned.